This book consists of seven chapter, the first chapter gives general introduction about the fibre. The second chapter gives an overview of the important of fibre an factors affecting its utilization by ruminants. Its also contains informations regarding methods to improve quality of fibre source as well as method in analyzing nutrient contents of fibre sources . chapter 3 throught chapter 6 contains informations obtained from a series of experiments related to fibre utilizations by ruminant. the experiments were designed to identity the most beneficial conditions afforfed by diets, feeding management and processing. in the last chapter (Chapter 7), general discussion and recomendation is presented in an integrated manner.